I have a Graflex RB, Series D, a 4X5 SLR, all original save for a back from the 1950s (so you can use modern sheet, roll, and Polaroid backs) and, as far as I know, it works. The black leather is all original and it has a focal plane shutter (T, 1/10 through 1/1000 sec). Lens is a No. 33 Kodak Anastigmat 7-1/2" f 4.5.

Looking down this page and over looking the typos you'll find it made from 1929 to 1945.
The link to the RB on line manual in the heading for this section will tell you how to operate it.
Value depends on a lot of things and its anyone's guess as to how many are still in existance and useable.
Charles

_________________The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.